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Salary: USD 148,000 - 222,000 / annual
Klaviyo is seeking a Senior Software Engineer to join the Customer Agent team, building AI-native conversational systems that help businesses create and execute better customer experiences at scale. The company processes billions of consumer profiles, messages, interactions, and conversion signals across 167,000+ customers.
In this role, you will design and build scalable backend systems and AI-powered product experiences that enable agents to reason, retrieve context, use tools, and take reliable action on behalf of customers. You'll independently own meaningful technical problems, make pragmatic engineering tradeoffs, and help evolve the architecture and quality of the systems you work on.
Key responsibilities include:
- Design and build reliable, scalable backend systems and APIs powering AI-driven customer experiences
- Build and evolve production agentic systems involving tool use, orchestration, context management, retrieval, structured outputs, and multi-step workflows
- Solve applied AI problems across retrieval and RAG, grounding, model selection, hallucination mitigation, and deciding when deterministic or hybrid approaches are better than LLMs
- Develop evaluation strategies using representative datasets, automated and human evaluation, regression testing, qualitative error analysis, and production signals
- Improve production reliability through guardrails, fallbacks, retries, observability, monitoring, and thoughtful failure handling
- Build asynchronous and distributed processing workflows supporting high-volume AI workloads
- Participate in on-call rotation and help diagnose, mitigate, and learn from production incidents
- Work directly with external customers and cross-functional partners to understand workflows, identify pain points, and translate feedback into product and technical improvements
- Monitor shipped experiences and use customer behavior, quality metrics, and system performance to guide iteration
The role may require up to 10% travel for new hire onboarding, client work, team meetings, and industry events.
REQUIREMENTS:
- 5-7 years of professional software engineering experience with strong foundation in backend systems and distributed applications
- Hands-on experience building and deploying generative AI or agentic AI applications into production for real users
- Proficiency in Python and modern backend frameworks such as FastAPI or Django
- Experience with asynchronous processing and distributed task or event systems such as Celery, Kafka, SQS, RabbitMQ, or Redis
- Strong knowledge of databases, data modeling, APIs, and persistence patterns used in production systems
- Comfortable working in cloud-native environments with technologies such as AWS, containers, Kubernetes, infrastructure automation, or CI/CD systems
- Ability to reason clearly about tradeoffs among quality, latency, cost, reliability, and implementation complexity
- Ability to operate independently in ambiguous environments, break down loosely defined problems, and make pragmatic decisions about what to build first
- Experience with and genuine interest in working directly with external customers to understand problems and improve products
- Care about shipping useful, reliable products with curiosity and sound engineering judgment in a rapidly evolving technical space
NICE TO HAVE:
- Experience training, fine-tuning, distilling, or otherwise adapting machine learning or language models for production use
- Experience with reinforcement learning or feedback-driven optimization
- Experience building evaluation infrastructure such as LLM-as-judge systems, evaluator calibration frameworks, benchmark suites, or AI quality platforms
- Experience operating AI systems at substantial scale, including optimizing inference cost, latency, or throughput
